摘要目的:评价低温缺氧-复氧处理的心肌成纤维细胞源性外泌体对大鼠低温心脏缺血再灌注时心室肌电传导的影响。方法:SPF级SD乳鼠，1~2日龄，雌雄不拘，差速贴壁法提取原代心肌成纤维细胞。传代至2~4代，待细胞密度达60%~70%，将其转移至4 ℃、95%N 2+5%CO 2条件下培养1 h，继续于37 ℃、95%空气+5%CO 2条件下培养24~48 h，随后提取外泌体。SPF级雄性SD大鼠24只，2~3月龄，体质量280~360 g，根据随机数字表法分为3组( n＝8)：对照组(C组)、低温缺血再灌注组(IR组)和外泌体+低温缺血再灌注组(Exo-IR组)。于平衡灌注前48 h时，Exo-IR组尾静脉无菌注射低温缺氧-复氧处理的心肌成纤维细胞源性外泌体1.5 ml (200 μg)，C组和IR组尾静脉注射PBS各1.5 ml。C组平衡灌注110 min；IR组和Exo-IR组平衡灌注20 min，停灌60 min后再灌注30 min。分别于平衡灌注20 min、再灌注15和30 min时应用微电极阵列标测技术获取左心室心肌传导速度(CV)、传导绝对不均一性(P 5-95)和不均一性指数(P 5-95/P 50)。 结果:与C组比较，IR组和Exo-IR组再灌注15和30 min时CV降低，P 5-95和P 5-95/P 50升高( P<0.05)；与IR组比较，Exo-IR组再灌注15和30 min时CV升高，P 5-95和P 5-95/P 50降低( P<0.05)。 结论:低温缺氧-复氧处理的心肌成纤维细胞源性外泌体可改善大鼠心脏低温缺血再灌注时心室肌电传导。

abstractsObjective:To evaluate the effects of exosomes derived from cardiac fibroblasts treated with hypothermic hypoxia-reoxygenation on ventricular electrical conduction during hypothermic cardiac ischemia-reperfusion (I/R) in rats.Methods:SPF neonatal Sprague-Dawley rats of either sex, aged 1-2 days, were used, and primary cardiac fibroblasts were extracted by differential adhesion method. The cells were passaged for 2-4 generations. When the cell density reached 60%-70%, the cells were transferred and exposed to 95% N 2 + 5% CO 2 for 1 h at 4 ℃, and then exposed to 95% air + 5% CO 2 for 24-48 h at 37 ℃, and then exosomes were extracted. Twenty-four SPF healthy adult male Sprague-Dawley rats, aged 2-3 months, weighing 280-360 g, were divided into 3 groups ( n=8 each) according to the random number table method: control group (group C), hypothermic cardiac IR group (I/R group) and exosome + hypothermic cardiac IR group (Exo-IR group). At 48 h before equilibrium perfusion, 1.5 ml (200 μg) of exosomes secreted by cardiac fibroblasts treated with hypothermic hypoxia-reoxygenation was injected into the tail vein in Exo-IR group, and PBS 1.5 ml was injected into the tail vein in C group and IR group each. Group C received 110 min equilibration perfusion. After 20 min of equilibration, the perfusion was suspended for 60 min (global ischemia) followed by 30 min of reperfusion in IR and Exo-IR groups. Microelectrode arrays were applied at 20 min of equilibrium perfusion and 15 and 30 min of reperfusion to obtain myocardial conduction velocity (CV), absolute conduction inhomogeneity (P 5-95) and inhomogeneity index (P 5-95/P 50) on the left ventricular surface of isolated rat hearts. Results:Compared with group C, the CV was significantly decreased at 15 and 30 min of reperfusion, and P 5-95 and P 5-95/P 50 were increased in IR and Exo-IR groups ( P<0.05). Compared with IR group, CV was significantly increased at 15 and 30 min of reperfusion, and P 5-95 and P 5-95/P 50 were decreased in Exo-IR group ( P<0.05). Conclusions:Exosomes derived from cardiac fibroblasts treated with hypothermic hypoxia-reoxygenation can improve ventricular electrical conduction during hypothermic cardiac I/R in rats.